%%%-------------------------------------------------------------------
%%% @author Anil Kumar S. R. <sranil@gmail.com>
%%% @copyright (C) 2010, 
%%% @doc
%%%
%%% @end
%%% Created : 26 Oct 2010 by Anil Kumar S. R. <sranil@gmail.com>
%%%-------------------------------------------------------------------
-module(b2bua_media_listener).

-behaviour(gen_server).

%% API
-export([start/0]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
         terminate/2, code_change/3]).

-define(SERVER, ?MODULE). 

-record(b2bua_media_listener_state, {port, socket}).

%%%===================================================================
%%% API
%%%===================================================================

%%--------------------------------------------------------------------
%% @doc
%% Starts the server
%%
%% @spec start_link() -> {ok, Pid} | ignore | {error, Error}
%% @end
%%--------------------------------------------------------------------
start() ->
    gen_server:start(?MODULE, [], []).

%%%===================================================================
%%% gen_server callbacks
%%%===================================================================

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Initializes the server
%%
%% @spec init(Args) -> {ok, State} |
%%                     {ok, State, Timeout} |
%%                     ignore |
%%                     {stop, Reason}
%% @end
%%--------------------------------------------------------------------
init([]) ->
    io:format("Inside b2bua_media_listener:init ~n"),
    {ok, #b2bua_media_listener_state{}}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling call messages
%%
%% @spec handle_call(Request, From, State) ->
%%                                   {reply, Reply, State} |
%%                                   {reply, Reply, State, Timeout} |
%%                                   {noreply, State} |
%%                                   {noreply, State, Timeout} |
%%                                   {stop, Reason, Reply, State} |
%%                                   {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_call(create_socket, _, State) ->
    case create_socket() of
        {ok, Socket} ->
            {_, Port} = inet:port(Socket),
            {reply, {ok, Port}, State#b2bua_media_listener_state{port = Port, socket = Socket}};
        _ ->
            {reply, error, State}
    end;

handle_call(_Request, _From, State) ->
    Reply = ok,
    {reply, Reply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling cast messages
%%
%% @spec handle_cast(Msg, State) -> {noreply, State} |
%%                                  {noreply, State, Timeout} |
%%                                  {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_cast(kill_process, State) ->
    {stop, normal, State};

handle_cast(_Msg, State) ->
    {noreply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling all non call/cast messages
%%
%% @spec handle_info(Info, State) -> {noreply, State} |
%%                                   {noreply, State, Timeout} |
%%                                   {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_info(_Info, State) ->
    {noreply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any
%% necessary cleaning up. When it returns, the gen_server terminates
%% with Reason. The return value is ignored.
%%
%% @spec terminate(Reason, State) -> void()
%% @end
%%--------------------------------------------------------------------
terminate(_Reason, State) ->
    io:format("b2bua_media_listener terminated ~n"),
    #b2bua_media_listener_state{socket = Socket} = State,
    gen_udp:close(Socket).

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Convert process state when code is changed
%%
%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState}
%% @end
%%--------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%%===================================================================
%%% Internal functions
%%%===================================================================
create_socket() ->
    case catch gen_udp:open(0, [binary, {active, once}, {reuseaddr, true}]) of
        {ok, Socket} ->
            {ok, Socket};
        _ ->
            error
   end.
